Electrical Circuits Prof. Jennifer M. Blain Christen BioElectric Systems and Technology

Units and Scaling

Units and Scaling Pico Nano Micro Milli Centi (none)10 0 kilo-10 3 Mega10 6 Giga10 9 Tera10 12

Units and Scaling What units do we use these words with? Meterslength Litersvolume Gramsmass Secondstime Voltsvoltage Ampscurrent Wattspower Ohmsresistance

Resistance Opposition to the flow of charge. When we measure resistance, we measure how much an object “resists” the electrons moving through it. We measure resistance in Ohms. We abbreviate this with an Omega, written like this .

How can we measure resistance? m V 9V Ohms Range

Sometimes, you try to measure something too big for me. I don’t know what to do, so I show you this. Try changing the range. If you are up to 2000k, and still get this…sorry!

Voltage is a potential difference. It is measured in volts. We can think of it like the height of a hill; only the relative difference matters. Current flows from higher voltage to lower voltage.

How can we measure voltage? m V 9V Volts Range

Electrical Current Definition: the rate of charge past a given point The more electrons that move through a wire in a given time, the larger the current. Current is measured in amperes or amps.

How can we measure current? m V 9V Amps Range

Power The amount of electrical energy used in a given time. We measure power in Watts. We can calculate power by multiplying current and voltage. 1 watt = 1 amp x 1 volt

We are going to use wires. Remember, wires are conductors inside of insulators. We can use them to connect two things together. conductor insulator

What is a sensor? Thermometers Pressure sensors Acceleration sensors Light sensors Your multimeter You!

We have some sensors… let’s see what they can do

What happens if we want to communicate over a long distance? Let’s try that! What happens to the signal?

Analog or Digital Analog signals are like the signals that humans perceive. They can have any value. Digital signals are like the signals that computers use. (Remember Boolean logic?) They can only have discrete values.

Analog or Digital Analog signals are elegant, but susceptible to noise. Digital signals are simple, and not very susceptible to noise. Which one would be better for long distance communication?

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